IIT JEE Practice Question and Answer
8Q: At 6′o clock a clock ticks 6 times. The time between first and last ticks is 30 seconds. How long does it tick at 12′o clock ? 3426 05b5cc731e4d2b4197774f7ec
5b5cc731e4d2b4197774f7ec- 166 sectrue
- 255 secfalse
- 336 secfalse
- 424 secfalse
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Answer : 1. "66 sec"
Explanation :
Answer: A) 66 sec Explanation: For ticking 6 times, there are 5 intervals. Each interval has time duration of 30/5 = 6 secs At 12 o'clock, there are 11 intervals,so total time for 11 intervals = 11 x 6 = 66 secs.
Q: 640 ml of a mixture contains milk and water in ratio 6:2. How much of the water is to be added to get a new mixture containing half milk and half water ? 1332 05b5cc731e4d2b4197774f7e7
5b5cc731e4d2b4197774f7e7- 1360 mlfalse
- 2320 mltrue
- 3310 mlfalse
- 4330 mlfalse
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Answer : 2. "320 ml"
Explanation :
Answer: B) 320 ml Explanation: Here total parts of milk and water in the solution is 6+2 = 8 parts. 1part = 640/8 = 80 old mixture contains 6parts of milk and 2 parts of water(6:2). To get new mixture containing half milk and half water, add 4parts of water to the old mixture then 6:(2+4) to make the ratio same. i.e, 4 x 80 = 320 ml.
Q: A box contains 90 screws each of 100 gms and 100 bolts each of 150 gms. If the entire box weighs 35.5 kg, then the weight of the empty box is ? 1849 05b5cc731e4d2b4197774f7e2
5b5cc731e4d2b4197774f7e2- 110.5 kgsfalse
- 212 kgsfalse
- 39.6 kgsfalse
- 411.5 kgstrue
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Answer : 4. "11.5 kgs"
Explanation :
Answer: D) 11.5 kgs Explanation: Screws weight = 90x100 = 9000gmsbolts weight = 100 x 150 = 15000gmsweight = screws + bolts => 24000 gms =>24 kgGiven entire box weight = 35.5kgempty box = entire box weight - weight => 35.5kg - 24kg => 11.5kgso the empty box is 11.5kg.
Q: fifteen persons are sitting around a circular table facing the centre. What is the probability that three particular persons sit together ? 2303 05b5cc731e4d2b4197774f7dd
5b5cc731e4d2b4197774f7dd- 13/91true
- 22/73false
- 31/91false
- 43/73false
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Answer : 1. "3/91"
Explanation :
Answer: A) 3/91 Explanation: In a circle of n different persons, the total number of arrangements possible = (n - 1)!Total number of arrangements = n(S) = (15 – 1)! = 14 !Taking three persons as a unit, total persons = 13 (in 4 units)Therefore no. of ways for these 13 persons to around the circular table = (13 - 1)! = 12!In any given unit, 3 particular person can sit in 3!. Hence total number of ways that any three person can sit =n(E) = 12! X 3!Therefore P (E) = probability of three persons sitting together = n(E) / n(S) = 12! X 3 ! / 14!= 12!x3x2 / 14x13x12! = 6/14x13 = 3/91
Q: A number of cats got together and decided to kill between them 999919 rats. Every cat killed an equal number of rats. Each cat killed more rats than there were cats. How many rats do you think that each cat killed ? 6170 05b5cc731e4d2b4197774f7d8
5b5cc731e4d2b4197774f7d8- 11009true
- 2991false
- 32000false
- 41000false
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Answer : 1. "1009"
Explanation :
Answer: A) 1009 Explanation: Given total number of rats = 999919 999919 = 1000000 - 81 = 10002 - 92 = (1000+9)(1000-9) = 1009 x 991.Since there were more rats than there were cats, 991 cats killed 1009 rats each.
Q: How many 6-digit even numbers can be formed from the digits 1, 2, 3, 4, 5, 6 and 7 so that the digits should not repeat and the second last digit is even ? 2224 05b5cc731e4d2b4197774f7bf
5b5cc731e4d2b4197774f7bf- 1521false
- 2720true
- 3420false
- 4225false
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Answer : 2. "720"
Explanation :
Answer: B) 720 Explanation: Let last digit is 2when second last digit is 4 remaining 4 digits can be filled in 120 ways, similarly second last digit is 6 remained 4 digits can be filled in 120 ways.so for last digit = 2, total numbers=240 Similarly for 4 and 6When last digit = 4, total no. of ways =240and last digit = 6, total no. of ways =240so total of 720 even numbers are possible.
Q: A man spend Rs. 810 in buying trouser at Rs. 70 each and shirt at Rs. 30 each. What will be the ratio of trouser and shirt when the maximum number of trouser is purchased ? 3078 05b5cc731e4d2b4197774f7b5
5b5cc731e4d2b4197774f7b5- 11:3false
- 22:1false
- 33:2true
- 42:3false
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Answer : 3. "3:2"
Explanation :
Answer: C) 3:2 Explanation: Let us assume S as number of shirts and T as number of trousersGiven that each trouser cost = Rs.70 and that of shirt = Rs.30Therefore, 70 T + 30 S = 810=> 7T + 3S = 81......(1)T = ( 81 - 3S )/7 We need to find the least value of S which will make (81 - 3S) divisible by 7 to get maximum value of TSimplifying by taking 3 as common factor i.e, 3(27-S) / 7In the above equation least value of S as 6 so that 27- 3S becomes divisible by 7 Hence T = (81-3xS)/7 = (81-3x6)/7 = 63/7 = 9 Hence for S, put T in eq(1), we getS = 81-7(9)/3 = 81-63 / 3 = 18/3 = 6.The ratio of T:S = 9:6 = 3:2.
Q: Each of the following series of statements is followed by four sets. Identify the set that is logically consistent.(a) The gap between the average starting salaries of teachers and those of other professionals has shrunk in recent years.(b) The average age of first year teachers is same as it was in 1975.(c) Starting teachers are no longer underpaid.(d) The extent of a persons formal education is a measure by which to determine his level of salary.(e) Over the last few years, the average starting salaries of other professionals have increased by 20% 1767 05b5cc731e4d2b4197774f7b0
5b5cc731e4d2b4197774f7b0- 1e,b,dfalse
- 2e,d,bfalse
- 3a,c,bfalse
- 4a,e,ctrue
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Answer : 4. "a,e,c"
Explanation :
Answer: D) a,e,c Explanation: The statements a,e,c are logically sequenced.